The Russian plan calls for safe zones to be established in rebel-held territory in the north-western province of Idlib, in parts of Homs province in the centre, in the south and in the opposition enclave of Eastern Ghouta near Damascus, the AFP news agency reported citing a copy of the plan.

The safe zones would end violence and allow for the return of refugees and the delivery of aid. They would be surrounded by checkpoints manned by rebels and government troops. Foreign troops could also be deployed in observer roles, the document said.

"One of the ways in which the ceasefire can be made to last is through creating safe zones or de-escalation zones," Mr Putin said, speaking in the Black Sea resort of Sochi after talks with Turkish President Recep Tayyip Erdogan.

"Mr Trump and I discussed this over the phone yesterday. As far as I understood, the US administration supports these ideas.

"Russia has held preliminary consultations with Damascus and Tehran. We all agree that mechanisms must be created to guarantee an end to bloodshed and create conditions for the start of political dialogue."

Mr Putin said aircraft "would not work" in the de-escalation zones "provided there is no military activity in these zones".

Further talks would determine how the safe zones would be controlled, he said.